Gate valves, also known as knife valves or slide valves, are a common item in industrial plants around the world. They are used in pipelines to control the flow of material through them. Their design ensures that pressure drops across an open valve are kept to a minimum. They are particularly useful when used with slurries or high viscosity liquids such as heavy oils, grease, or thick food products. However, their design also causes accelerated corrosion and erosion of seat and wedge surfaces due to their exposure. Over time, this erosion and corrosion will lead to failure of the valve requiring replacement which is not only costly from a time and labor standpoint, but from lost production from the associated industrial process as well. One (1) approach has been to attempt to construct gate valves with liners to combat these disadvantages.
Various attempts have been made to provide gate valves with liners for industrial use. Examples of these attempts can be seen by reference to several U.S. patents including U.S. Pat. No. 2,893,684; U.S. Pat. No. 3,993,092; U.S. Pat. No. 4,009,727; U.S. Pat. No. 4,201,365; U.S. Pat. No. 7,100,893; and U.S. Pat. No. 7,350,766.
While these apparatuses fulfill their respective, particular objectives, each of these references suffer from one (1) or more disadvantages including an undesirably substantial number of mechanical connections and specialized tools or machinery required during manufacture, installation, operation, and repair; limitations in molding, manufacture, and assembly of various components, particularly liner constructions such as found in U.S. Pat. No. 3,993,092 and U.S. Pat. No. 7,100,893; and eventual leakage and failure due to fatigue on gate or liner portions of the apparatus. Accordingly, there exists a need for a knife-style gate valve and liner without the disadvantages as described above. The development of the present invention substantially departs from the conventional solutions and in doing so fulfills this need.